The essence of my research is understanding how and why landscapes change over time. I am currently working on how the lower Ohio River valley has changed over the past 100,000 years. The primary force at work has been glaciation and deglaciation of the northern hemisphere, but neotectonic deformation within the Wabash Valley seismic zone, climatic changes unrelated to glaciation, and natural fluvial processes have also played a role in shaping the valley. Sediments are an excellent archive that preserve paleoenvironmental conditions if you know what they are and how they are distributed in time and space, so my research relies heavily on geologic mapping and geochronology. Identifying the processes that worked thousands or tens of thousands of years ago involves multiple disciplines, including sedimentology, hydrogeology, pedology (study of soils and paleosols), paleolimnology, palenology, and even structural geology. Geomorphology is anything but mundane!
Specifically, I am working on several aspects of the late Pleistocene and Holocene evolution of the lower Ohio River Valley, which is the focus of my PhD research. The lower Ohio River Valley is interesting for a number of reasons. First, it was a major drainage outlet for the Laurentide Ice Sheet. The bedrock valley of the Ohio RIver was deep prior to glaciation, so there was plenty of accommodation space for glaciofluvial sediments, and deposits are thick in this part of the valley. These sediments include outwash, multiple loess sheets with paleosols, complex deltaic and splay deposits that lie within and are interfingered with slackwater/backwter lake deposits, and I even found a buried beach sand in one core. Holocene sediments are superimposed upon or are inset within many of these older sediments, so developing an accurate stratigraphic framework can be challenging, especially in the region where the Wabash River joins the Ohio River.
The thick and diverse sediments In the lower Ohio Valley have implications for the seismic hazard of the region. This area is seismically active. In the past 20 years it has produced 4 earthquakes larger than M 5.0., and the sediments are susceptible to seismically induced ground failure (liquefaction) and amplification of shaking. I have found paleoliquefaction features that indicate there have been major earthquakes in the past. I have also found some compelling evidence that suggests neotectonic deformation diverted the course of the Ohio River at least once during the Holocene. But perhaps most tantalizing is this: because my study area lies between the Wabash Valley Seismic Zone and the New Madrid Seismic Zone, and the Ohio River flows from one zone and through the other, research here may one day help us understand if and how the Wabash Valley and New Madrid Seismic Zones are related.
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